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June 30, 1925. 1,544,381

G. w. ELMEN ET AL METHOD-AND SYSTEM FOR AMPLIFYING VARIABLE CURRENTS I Filed April 9 1918 //7ve/7/0r,s V Gusfaf W [/me/z Car/E Orf.

Patented June 30, 1925.

I *P- rE-N- 01 65;

eus'rarwi mmm; or BOGOTA, NEW .r-EnsnYQ-nnn CARL F. 011T, OF-NEWYORK,IN."Y'., 1 AssIGnons-mo-wnsTEmI smc'rmc COMPANY, "INCORPORATED; orimw iroax,

- 'I L Yi,A'COBPGItATIONDENEW ro'mz.

' MEET hob; SYSTEM FOR AMPLIFYING VARIABLE CURB/ENTS.

:1 -Applicatin filed April 9, 1318. Serial No. 227,564.

I y .cqm m-i Be it'known that e,'GUs'rAr Emmu it r i a, at Bogota, in the county. offBergen of New lersey, and rat" blemlork, lingthe county 'of .New York,

w sd 1 nwan wi -fi e l 'p q ,nlentsiii'Me'thods; and Systems for Amplify.-

variablelflui rexits oi yvhich'the follow; ring. is a'ffull, ;clea'n',:- concise,

lz r vp 'i 'i t' I a. This inventi nrelates to 1 methods of: and

. nd e e 1 gfor amplifying uariablecurrents and more rrarfiwlarly 9 s na ng: systems in -which;. alternating .currents are subjected to h 'eetion fiwe ig ki 9n e v a mo 'i oi l-oew a iiiagneticn aterialu: g v Anoth r, h'ect eithe -invention to prowid q ie e i r lshei si g th P meability of hegnetic 1 cores; for alternating l,

Lfluxesat initial lowflux'den'sitiesge 4 .further. objectiof the invention is to provide a variable alternating current impedance, the value of-which may be'readilycontrolled.

A still further object ofthe invention to providemeans fornamplifying yeak signal ng currentslt is well known a core of magnetic material is maden path vfor alternating fluxes of diflerent frequencies the higher y .teresis --.It has been discovered. that .not only is gtlie hysteresis efieet ,for the low frequenredueed, but-the permeability of the e. considerablyfincreasedby,the presenceof the gher' frequency flux, ,It is found. that for a the, lo vyugfrequency flux and reaches a inaximumyalue at;a relatively. lowde'nsity,-

:In operationfthe m1cr'opho'ue 2 seryes to aftenwhich the; permeability decreases.

the'primary winding ofainaig'netic device whichgifiprises a toroidal core of nragnetic' material;

State,:oitf liewYorlig -v resgmectively, have in;. p p

lower frequency current'fiowing'inthe;out-

cuit; pg the plimeability of ;g iven,..value. o fhigh frequency flux, thefoi the low hfrequency flux in-. .creases xzery rap dly; .with increasing density,

second associate with res pondingly changes lthe permeability of the-magnetic core for the flu s'et iipfhy the put circuit An increaseiin the perm'ahility of the core, and therefore th'e nia gxietic flux produced by the low frequency I urrent, uncreases the induction and therefore he pedance oi the ;portion] of theilowerflfrequency circuit directly associated yith; thecore, vhile decrease in the permeability of the core res'ults in decrease inthe impedance of this portion of the lower frequericy 'eir the signaling system, :while 'Eigs. 2 and illus- I trate respectively atranjsrnitti ngl station and .u receiyln'g stution fOlifildlO signal ng.

Referring to Fig{l1 a generate l"p'rdu c ing oscillations of -=high.- frequency-gr nt a 1 transmitting station. A is shown connected in a series circuit including the microphone2, a

variablev resistance 3 and windings 4 and 5 respectively of toroidal ma netlc cores 6 and 7. A generator 8 of oscillations of frequency g is connected by potentiometer 9, in a circuit 10 including windings 11 and 120i toroidal cores 6 and 7 respotiye'ly, a. variable inductance 13 and a variable cal pacity -14. Circuit-l0 extends toali receiving station B and includes the primziry xyinding of a transformer 15 the secondary w i liding of which is included in the-receiving cir cuit. As-shownin the drawin circuit 1O is grounded-a s'; a t- G at both 1: ereceiving and transmitting stations arrangement may obviously be replaced by one employing a metallic. returnconductor. a The secondary windingof transformer 15 is connected through a detector-l) to s telephone'gipceiver R which is shuntedb the usualcondenser C. -1,;

plied by the circuit pit he ,w amplitude seuucrehs e s .dimgh in opposition with respect to the windings 11 and Eta-nil uccordinglyumcurrerrhof ffrequency 7' is set up in circuit 10, since the electromotive forces induced in windings 1'1 'and 712 are \oppositel-y directed and aequa'l to each other. 51 be :number of'tiurus' of windings 11 and 12 may be so chosen that these clectromotive forces completely neutralize each other. W'mdings =11 and 12 are sup l plied by generator 8 with oscillations of frequency which is preferably 'much 'lower vthan frequency 1-. Circuit 10 may be tuned as desired "by means of variable inductance 13 and variable capacity 14. Current through \\'inrlings'11 and '12 gives rise to a 'fiux in cores 6 and 7, the value of which is dependent upon the permeability of these cores Lifer flux of -lrequenc-y g. lVhen these.

-.cores are sulrgected to llugher frequency flux,

such -as that resulting from the oscillations of'l reque ncy 'rjt-he hysteresis energy which it 'is necessary to supply .for maintenance of the low frequency flux, is much reduced.

if," y proper .jdelsign of the cores 6 and 7 and windings 11 and 12,"the density of the flux of frequency q is ikept relatively "low,

' they-higher frequencyfiuxjhas .the further ellect of markedly changing the permeabili'ty 'forftheflr xof frequency g. This causes a corresponding change in the inductance and therefore in theimpedance of. windings 11 and 12 folaalternating current of fre- 'qu cncy q, andthe variations intlie amplitude this current are attended with cor responding variationsinthe current in the receiver circuit 'atstat-ion B. Preferably the density of thefflux of frequencyg should be maintained wifliin the range .throughout' .wliich th'e high frequency flux produces the most rapid change in permeability. If g is an ultra audible frequency, the detector D will setup in the circuit of the receiver a low-frequency signaling current correspond ing to therariations setup by microphone 2 The function of the magnetic cores 6 and 7 and their associated .w ndings is in this instanceto enable modulation of the current.

.of circuit10in accordance with signaling I site corners 43-,and supp in .the current of the circuit of generator 1.

currents] Viewed broadly. however, the. magneticdewce serves to amplify variations" 5" variable capacity 26a P winding of 4 a t ransform er 27. windings 19 and 20 are -\mund on cores 21 and 22 in opposition with respect to the windings 24 and 95 as in the case of the system of Fig. 1. Capacity '26 :permits tuning 0f .:the ciriouit'of :generator 23, asifor example,ato the-.fiequency. q or to rthe nneanifi equenqy obamy -hamd rfrequencies he operation offfthe system of Fig. 2 is analogous to that of "Fig. .1, with'the exception that unguided electromagnetic Waves are transmitted in the system 'ofF- ig. 2 and the frequency should iiheiefore be made suchas to permit of efficient r'adiation.

Referring "to theira'dio receivfigigsystem of Fig. 3, ,the circuit of antenna 30 includes the tun ing condenser and Findings '32 and 33 of magnetic cores 34"ii1id f-lfire'spectively. lVindings 36 and 37 ,of cores 34-aiit1-35-constitute two idiagonafly op o'si te arms of a Wheats'tone bridge cf whic the -o'ther arms are "windings 38=and '39 of cores' l'i) and -41. The generator '42'connedtedthrotrgh a series tun in g condenser 47 to the'dia anal-1y oppo- 4 electrical oscillations or frequency to =tuW=he-atstone bridge. Connected betwe'fij tlie fotliejr two corners of lfh'e".\Vlreatston'e"bridge is {conductor '45 ,wliich' includes the primary 'winding of the waster-anemic. The input winding of a defieeeer m preferably' of the vacuum tube type, serves as thelsecoiida-ry of "transformer-.46 and (31eoutptit winding 'of'ithe "detector is coupled to'the localf'ciic-uit of "The operation o'fthis' receiving system will now be described. 'Iiicom'ingcvaves modified or modulated, astli'e'- casetrraybe, in accordance with sig nals,;stinp high frequency oscillations inthe antenna ;circuit. li -the frequency of oscilhftion s b'e (1, cores '34 and 35 will lr'e 'sulfiected 'toal'tern'ating flux of fiequency. At ,a-iiy'time WilQn nofsignals m1 ei fg'ttansmittd;"the lvlieatston'e "bridge is balanced for o's cilla.

v .t'ron s "supplied ,the generator 12, such balancing beingreadily I accomplished"; by making the cores 34,:35, mime il i'alike and by-propefly choosingtheconstaiits of each brid e arm incluiling the number of turns of ghe core windings. 'Dnrin' honsignaling periods, no current wil flow through conductor 45. During periods of incoming. signals, the high frequency flux varies the, impedance .of windings" 36 ,and 37 .to the lower frequency current 8 intaccordance with the variations in the i incoming signal oscillations. The-resulting un balance causes-current of frequency 8 to flow sour-rent -undergoesvariations in amplitude in conductor 45 and a response corresponding to the original signals is obtained in receiver R.

The frequencies of the oscillations supplied to the primary and secondary windings of the magnetic amplifying device may take a wide "range, providedonly that the input current have a considerably higher frequency than the output current. As a specific example, the frequency 1" may be 200,000; g maybe 50,000 and 8 may be 10,- 000 cycles per second.

In the circuits of each of the three figures of the-drawing, theamplifying arrangement is substantially the same and consists of a magnetic core device having an input circuit winding-and .an output circuit winding.

The input winding is supplied with high frequency oscillations varied in accordance with signals, while the output winding is supplied: with lower frequency oscillations. The-high frequency-input oscillations pro- .duce aflux which-greatly increases the imedancein .the magnetic core device for the ow frequency oscillations, and accordingly small changes in the input current are attended by 'verymuch larger changes inthe output current.- It is in this sense that the magnetic device is termed an amplifier.

Since. in'the systems disclosed the output corresponding -to g incoming signaling currents, .thetv magnetic amplifier serves as a .modulaton-fi- The circuits of output generator 8, 23 and may,-;asi previously vset-forth, be tuned :to;r esonancei.' The change of inductance of X the magnetic amplifier windings will alter this condition of: resonance and the current in the output circuit be further varied if such tuning is used. However, this-is not an essential condition "and the output generator circuit'may be untuned if desired.

As previously mentioned one effect of the high frequency flux is to decrease the hysteresis energy which must be supplied by the generator in the output circuit of the magnetic amplifier. This effect may, however, be relatively small at the flux densities at which the change in permeability for the low frequency flux is most rapid.

While three specific arrangements involving this invention have been illustrated, it is to be understood that it is capable of general application and that the scope of the invention is to be restricted only by the appended claims.

What is claimed is:

1. The method of transmission which comprises subjecting an alternating current to the action of a magnetic impedance, varyin said magnetic im' edanc'e' in accordance W ld! modulated oscil ations' of frequency higher than said 'current wherebyesaid altermung car-rent is varied in magnitude inaccordance with the modulations of said oscillations, and transmitting the energy of said varied alternating currentv to a remote signaling station.

2. The method of amplifying currents which comprises subjecting a magnetic core simultaneously to two alternating magnetic fluxes of different frequency maintaining the lower frequency flux at low density, and varying the value of the higher frequency flux in accordance with changes in the currents.

3. The method of signaling which comprises varying an alternating current in accordance with signals, varying the amplitude of a secondalternating current of lower frequency than the first in accordance with the amplitude variations produced in said first-mentioned alternating current, and transmitting to a distant station energy cor responding to that of said varied amplitude current. i

4. A magnetic control device comprising a magnetic core, an input circuit and an out put circuit associated therewith, a source of high frequency current in the input circuit. a source of lower frequency current in the output circuit. and means connected to said output circuit for transmitting the energy of said lower frequency current to a remote re ceiving station.- I

-- 5. An amplifying system: comprising a circuit, means for supplying thereto alternating current of a given-frequency, a .second circuit, means for supplying to said second circuit an alternating 'current'of frequency higher than thatsupplied to said first circuit, means for varying said higher frequency current, means for. varying the impedance of said first circuit in accordance with the amplitude variations produced in said higher frequency current, and means for transmitting the varied energy of the current in said first circuit to a remote point.

6. A magnetic modulator comprising a magnetic core, two alternating current circuits including sources of different frequency currents having windings associated with said core, a signal transmitter in the circuit of the higher frequency current source, and means connected with the circuit of the lower frequency current to transmit the energy thereof to a distant point.

7. A magnetic amplifier comprising two toroidal cores, an input circuit and an output circuit each of said circuits having windings associated with each of said cores, said windings being so related that the electromotive forces induced in said output circuit upon variation of the current of said input circuit are equal in value and opp'osite in; direction, means for impressing an alternating E. upon said output circuit,- means' for impres ing a higher frequency alternating M. upon said in 1 p'titci remit; and meahs I fortransferring to a distant point energy corresponding. to that fif tll'b current setiip'in saidoutputcircuit bythe E. M. F. impressed thereon: i S' The methodwhich c omprises iirodncing ca'rrier Waves and higher frequency os illations; modifying said 3 higher frequeney I oscillations-fin accordance with speech, causing said modified oscillations to vary the amplitudeof' said car'rien'waves, and transmitting the energy 0f said Varied amplitude carrier waves to a remote station. 9a The'methdd *ofincreasing the permeability of ma etic materialto an alternati ng flux whici consist-s in maintainingf said flux ther eitl' at IUW fluX HBnS-ityand simultaneously subjecting-the material to a higher frequency flux. 5

'10. A' system-for magnifying electrical Variations comprising a magnetic *inaterial,

means for settingup "in said material-alternating fluxes of two widely difierenthfre- "quenci'es' of such small'ifiuzrmdensities that the permeabilityof the material for the flux of 1w *freqlien'cy' is increased" by I the high frequency flu'x; means for warying-athe Fhigh jfiequehcy'flux inaccordancewith said varia- 'tions tdbemagnified'; an'd wcir'cuit foritrans- Y *latln'gi the 1 resultant: changes? iii 1 permeabili ty into electrical waves modified iih'ac'coi'dance with said variations to be magnified,

511 9-111 combinatiomi 'a-'iource: of 5 carrier waves; a source 'of' higher =frequency'i oscillations, means 'ftir modifying said'zoscillations Z in accordance with =si3eech= means for Varyifig 'thef amplitude of :shid .cai'rieif waves a in accordance with the variations introduced uwzwes to=a distant pointw hetic modulator having'an input circuit and an output circuit electromagnetic'ally: asso ciafed with a common magnetic "core; means for supplyl'rig-wavesto said-output circuit, means qffior-svsupbly-ing mhigher- 2 frequency speech? 'm'odifi ed Waves to said inpufi" circuit to vary the-=i1n1jedance ofusaidoutput circuitglto contlbl the wavesssupplied to said output circuit in accordance-Withwspeech, and means for preventihg transfer of 'waves of said-higher frequency to said output circuit. 1391x111 magnetic modulating; system, a circuit; for transmitting to 1.-a #distance; a source of alternating! current fivaves fon supplying -sa id-' circuit, a:- oi'rcuit" local F1301: said modulating rsystemi containing; :ai isourc'e -of alternating currents of. a- Tfrequen'cy; liigli' in conripa-risont with i the --fre'quency of said first mentioned source, ahd' h1a ns- 'f0na1tt1ing the chara'cte risti'c's of said maginetic 5 'system *t'o :vary 'the -altern-ating- -eurr'ent inith'e :fi'ist mentibnedcircuit comprising mea ns for "w anyihgrth h-i'gh f're uencyurrent 'ii'ri th innah high frcquency libuit. v:;m: ;m; 5 14; In combinatiqm'g ineane fon gleamin oelgiodicgcur'rent mans fer -prorilueiii'g alterhating current of -'areq1incyf higher 5 ithan thatflo'f said eriyliccurrent;mneansfibr;controlling mid-alternating 'curreht' in" warr'sbord ance- {withontrol: ene -gypmidnmeansfifor warying sai'dperiedicejurr'ent izb accordance H withwhe controlvariatinsi in said altemau in; current and to the practical ex clusion meander; ime. 1218. cAR r0RTs In itness, 

